Solar after the Storm

DIY Solar + Batteries for Puerto Ricans

The vast majority of Puerto Ricans have been living with no electricity since Hurricane Maria hit on September 20th, 2017. Government officials estimate repairing the already ailing electricity grid could take 3-6+ months. For average Puerto Ricans, this means no lighting, refrigeration, cooling or ability to charge devices at home. Thankfully, there are a number of solar lighting, charging, and DIY solar systems that can be provide power while the grid is being fixed. This guide will give Puerto Ricans a primer on the various solar power options to get through this dark time.

 ~ Aquí está este artículo en Español. ~ 

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Budget Solar Lighting and Charging Options

There are number of budget solar lights and chargers that will allow you to have basic lighting and device charging. These can’t provide power for things like fans or refrigerators but they will give you some electricity for very little cost.

Solar Lighting

d.light A1 LED Solar Rechargeable Solar Lantern ($10)

D.light’s are designed to replace kerosene lamps in developing countries. They are durable, affordable and tested in a variety of conditions.

Nokero N233 Solar Light-Lantern (~$20)

Nokero’s lights have also been used in dozens of countries to provide a durable, long-lasting kerosene alternative.

source: https://www.treehugger.com/gadgets/35-inflatable-waterproof-solar-lantern-will-also-charge-your-phone.html

LuminAID PackLite Max USB Solar Inflatable Lantern ($30)

LuminAID’s inflatable lantern provides long-lasting light and 5 brightness settings.

Solar Charging Packs

source: https://9to5toys.com/2017/08/29/ravpower-solar-charger-review/

RAVPower 15000mAh Outdoor Portable Charger Solar Power Bank Dual ($30)

RAVPower’s charging station would charge an iPhone 7 4.2 times, an iPhone 7 Plus 3 times, and the Galaxy S8 2.8 times. The small solar panel will not charge this device very quickly but it will work.

RAVPower 16W Solar Panel with Dual USB Port Waterproof ($52)

RAVPower also offers a well-reviewed portable solar panel with 2 usb outputs. This is designed to charge devices vs. storing power (like the power bank).

Powering Appliances with Solar

Lighting and charging devices is a huge win for most people. But you might still be wanting some power for other appliances like refrigerators and fans. This part of the guide will cover buying and building a solar panel and battery system for your home. These DIY off-grid solar panel systems have gotten dramatically cheaper and easier to assemble in the last couple of years. Homesteaders, survivalists, vanlifers, and homeowners of all types are meeting their electricity needs without hassle, noise, fuel costs, or great expense.

Powering Appliances: Calculating Power Needs

The first step toward building a basic solar + battery panel system is figuring out your bare minimum power needs. What do you need to power exactly (e.g. lights, fridge) and how much power do those each need? There are a number of calculators and resources to help with this. We’re going to use the kWh/hour and kWh/month numbers given by the City of Santa Clara’s Appliance Energy Use Chart. This guide will focus on powering lighting, refrigeration, fans, and electronics.

Lighting

Flashlights are the first thing most people reach for in a power outage. Being able to see, work, cook and read at night makes life a whole lot easier. As you probably noticed in the previous section, lighting is quite an easy thing to power with solar panels and batteries. Many LED bulbs use under 10 watts and most fluorescent bulbs use under 20 watts (this is not much). It’s possible to light a home with minimal power draw on a battery.

Refrigerators

Refrigeration is one of the next top priorities for electricity. Refrigerators vary greatly according to electricity consumption (with newer models consuming up to 75% less energy than older models). An older refrigerator (mid-90s) might use around 150 kWh per month while the newer energy stage models use around 35 kWh per month.

Fans

Air conditioning is downright amazing but it uses a lot of energy. It cannot be used in a minimal solar panel system. Portable fans are the next best option for staying cool and most are relatively efficient. Most portable fans use around 0.03 kWh per hour.

Electronics (TV, Phones, Laptops)

TVs, phones, and laptops are arguably necessities in modern times. You can live without them but most of us don’t want to. These electronics vary greatly in their electricity consumption. TVs use between .1 and .4 kWh per hour while laptops tend to use 0.02 – 0.05 kWh per hour. Charging an iPhone 6 completely uses about .105 kWh while a Samsung Galaxy S8 take about .115 kWh to charge.

Calculating kWh

Now that we know what we’re going to power, we need to calculate the energy this system must be able to generate and store.

Refrigerator: Approximately 75 kWh per month. Older fridges will use more energy and newer fridges will generally use less. We went with a number in the middle but you should check the date and energy consumption of your fridge (it’s almost always written inside).

Fans: 0.03 kWh per hour * 12 Hours * 30 days * 2 fans = 21.6 kWh per month

TV: .12 kWh per hour * 2 hours * 30 days = 10.8 kWh per month

Laptop: .03kWh per hour * 3 Hours * 30 days = 2.7 kWh per month

Lighting: 0.015 kWh per hour * 4 Hours * 30 days * 5 bulbs = 9 kWh per month

75 + 22 + 11 + 3 + 9 = ~120 kWh needed from solar panels + batteries

Note: These items can make life a lot better. That said, they can be cut out or severely minimized to limit the amount of electricity consumption. Skipping refrigeration would allow you to have a much smaller/cheaper system size.

Sizing and Building a Solar Panel System

How big of system do you need to sustain 120 kWh of use over a month? Sunny Puerto Rico gets around 5.5 hours of peak sunlight per day. Using the PVWatts System Size Calculator, we calculate a system size of 1000 Watts. The PVwatts calculator says that with a 1kw system we can generate around 1500 kWh per year (or around 125 kWh per month).

What exactly do you need for a 1kw solar panel and batteries system? To generate 1kw of electricity, you need to get a set of panels that adds up to 1kW (e.g. 4x250W panels). For the batteries, the calculation is a bit more complicated. Here’s the math:

120 kWh per month / 30 days in average month = 4kWh / day

4kWh per day * 2 days (for backup storage) = 8kWh or 8000 Watt-hours

8000 Watt-hours / 12V batteries = 666 Ampere-hours (Ah) of storage needed.

The system will need solar panels, batteries for storage, a charge controller to monitor charging and prevent overcharging, and an inverter. Both Amazon, Walmart, eBay, Home Depot, and numerous other online retailers offer solar panels and solar panel kits. We’ll review both the options for buying these parts separately or in a kit.

Solar Panels

Panels are, no surprise, the engine of any solar energy system. Here are some well-reviewed solar panel options.

  1. Sainty Solar 255 Watt 24 Volt (~$290 on Amazon)
  2. Solar Panel ALLPOWERS 18V 12V 100W Bendable SunPower (~$160 at Walmart)
  3. Grape Solar 265-Watt Polycrystalline Solar Panel (4-Pack) (~$330 per panel or ~$1320 at Home Depot)

Batteries

For 8kWh with a 12V system, you’ll need roughly 660 Ah (It is hard to find 1 battery of this Ah; it is easier to connect 3 to 4 batteries in series to make up 600 to 700 Ah).

Batteries are used to store the power generated by the panels so it can used later. Batteries come in many types but sealed lead acid (SLA) batteries are going to offer the right balance of maintenance, price, and storage capacity for most setups. Here are some well-reviewed battery options.

  1. 12V Mighty Max 200Ah 4D SLA AGM Battery Replacement for Solar Systems (~ $370 from Amazon). Use 3 of these to get 600 Ah of battery capacity
  2. 12v 255ah 8D Deep Cycle AGM Solar Battery (~ $350 from Apex Battery). Use 3 of these to get 765 Ah of battery capacity.
  3. Universal UB121000-45978 12v 100AH Deep Cycle AGM Battery (~ $160 from Amazon). Use 7 of these to get 700 Ah of battery capacity

Note: We excluded batteries that explicitly did not ship to Puerto Rico.

Charge Controllers

Charge controllers monitor solar panel production and prevent batteries from getting overcharged. Here are some well-reviewed charge controller options.

  1. ALLPOWERS 20A Solar Charger Controller (~ $20 at Amazon)
  2. Renogy Wanderer 30A PWM Solar Panel Charge Controller (~ $50 at Walmart)

Inverter

Inverters convert DC power generated by solar panels into AC power that can be used by devices, refrigerators, and lighting. Here are some well-reviewed inverter options.

  1. AIMS Power 2000 Watt 12 Volt Modified Sine Inverter (~ $190 at Walmart)
  2. SOLAR PI20000X 2000W Triple Outlet Power Inverter (~ $215 at Amazon)

Racking

The solar panels on your roof need to be held at the right angle to the sun (18 degrees in Puerto Rico) and they need to be held down from the wind. This can be done with a rooftop racking system combined with sandbags. Here is a well-reviewed racking option.

  1. Adjustable Solar Panel Mount Mounting Brackets Folding Tilt Legs (~50 each at Amazon)

Approximate total price:

Solar Panels: $1200-1500

Batteries: $1100-1400

Charge Controller: $50-100

Inverter: $150-300

Wiring: $50-150

Racking: $100-300

Total: Approximately $2600 – $3700

How to Wire and Setup

The final step is to wire up the solar power system at home to start generating power.

  1. The 3-4 solar panels need to be connected in series and then connected on the negative and positive ends to the charge controller.
  2. The batteries need to be connected also in series (positive to negative), except at the ends, where they will also be connected into the charge controller.
  3. The charge controller needs to be connected out to the inverter.
  4. Extension cords and household appliances are then connected into the inverter.
  5. Tilt panels facing south at an 18 degree angle.
  6. Panels and racking system need to be held down by sandbags or other weighting.

Recommended Reading

There are a number of blogs, videos and guides that explain off-grid solar in more depth than we can here. Here are some our favorites to learn more about various setups:

DIY OFF GRID SOLAR SYSTEM on instructables

Long thorough guide to setting up an off-grid solar panel system.

My Modest Solar Setup

Off-grid solar guide with extensive wiring diagrams.

How we built our off-grid van solar system

Off-grid tutorial for vans that would easily apply to small houses.

Van Life – Our Amazing Stealth Solar Power Set up! (Video)

Shows the wiring and thought process behind setting up an off-grid solar system for a van (using Renogy brand gear).

Going Off Grid: A Detailed Look At Our Solar Panel Setup

Another long and thorough guide for building a small off-grid solar panel system.

Puerto Rico Solar Installation Resources

The internet has a wealth of resources but sometimes it’s nice to talk to a professional. Here are some Puerto Rico based solar professionals we recommend chatting with.

Integrated Solar Operations

Ralph Diaz

Web: www.isoenergiapr.com

Tel: 787-919-7701

Email: info@isogrouppr.com

1250 Ponce de Leon Ave suite 905

ACONER (Asociación de Consultores y Contratistas de Energía 
Renovable de Puerto Rico)

Email: aconer.pr@gmail.com

Web: www.aconer.pr

AZ Engineering

Angel Zayas

Tel: 787-768-3851

Email: info@azeng.net

Web: http://www.azeng.net

New Energy Consultants & Contractors

Tel: 787-291-0020

Email: info@newenergypr.com

Web: http://newenergypr.com